Cameras using a solid state image sensor such as a charge coupled device (CCD) and a complimentary metal oxide semiconductor (CMOS) image sensor have been rapidly distributed. To increase resolution of a camera, a degree of pixel integration of a solid state image sensor is increased. Also, the size and weight of a camera is being reduced through improvement of performance of a lens optical system included in a camera.
In a general lens optical system of a camera, a large number of lenses are used to secure performance of the lens optical system, e.g., to secure a large angle of view and to correct aberration. However, when the lens optical system includes many lenses, it may be difficult to make a compact and lightweight lens optical system. Furthermore, due to a characteristic of a camera lens, the size (or outer diameter) of the lens increases as the lens is closer to an image sensor for ensuring a light path. For an ultra slim lens optical system having a relatively short focal length, while a total length of the system decreases, the size of a lens increases and thus the outer diameter of a camera increases. In this case, it may be a problem to adopt the camera to a compact device such as a mobile phone.
Accordingly, there is a demand to develop a compact lens optical system having a relatively wide viewing angle and being able to easily correct aberration.